Late tries from Anthony Laffranchi and Tony Puletua earned Saints the spoils to push them up to third in the Super League table. Paul Wellens and Josh Jones also scored two tries each for Saints, while Jonny Lomax scored one and Tom Makinson kicked a trio of goals.
Saints raced into a 26-0 lead but they were far from home and dry. Scott Taylor and Sam Latus both scored twice as Hull KR, who trailed by 10 points at the break, went in front by two points. Blake Green also went over while Michael Dobson kicked four goals - but Saints responded late on to claim victory.
Hull KR"s bus broke down to cause them to arrive late at Langtree Park and they were slow out of the blocks as, after a penalty, scrum-half Lomax ghosted through to plant the ball beneath the posts. Saints then continued to press and the pressure told when Lomax held the ball up well for the supporting Wellens to go over for a try.
Lee Gaskell"s boot was profitable with the young stand-off"s grubber kick bouncing kindly into the grateful arms of Wellens, who was left with the formality of picking up and touching down. Makinson"s goal made it 16 points after as many minutes and Saints were soon back for more. Another fine attacking kick, this time from Jon Wilkin, was collected and touched down by teenage centre Jones, with Makinson again slotting the conversion.
Rovers then had a spell of pressure, but Constantine Mika"s haste to offload backfired when Tony Puletua picked up to spark a length of the field move. The New Zealander ate up the early yards before offloading to compatriot Francis Meli, who took play upfield before supplying the scoring pass for Jones.
But Rovers roared back with three tries in the last 10 minutes of the half to make it 26-16 at the break.
Scott Taylor cashed in a spilled Meli ball to go in for his second try, goaled by Dobson, and Rovers hit the front for the first time when Josh Hodgson touched down Dobson"s grubber kick, the latter"s conversion putting the visitors two points in front.
But eight minutes from time, on the back of a penalty and a six again, Laffranchi ran a good line to crash through from close range.
Makinson missed the easy conversion to add to the tension. But late in the game, Meli broke down the wing and Puletua forced his way over to make sure of victory.
Wigan Warriors were stunned by Bradford Bulls at the DW Stadium, the league leaders falling to a 30-22 defeat in front of a shell-shocked home crowd.
Salford City Reds took full advantage of the Warriors' slip-up, beating Warrington Wolves 48-24 to move to close the gap at the top of the table to a single point.